Anti-arrhythmic quaternary salt compositions and methods of use

ABSTRACT

WHEREIN X- IS THE ANION OF A PHARMACEUTICALLY ACCEPTABLE NON-TOXIC ACID, TOGETHER WITH A SUITABLE PHARMACEUTICAL CARRIER.   X(-)   1-((H3C)2-CH-N(+)(-CH3)2-CH2-CH(-OH)-CH2-O-)-NAPHTHALENE   1. A PHARMACEUTICAL COMPOSITION WHICH COMPRISES A THERAPEUTICALLY EFFECTIVE AMOUNT OF A COMPOUND OF THE FORMULA

United States Patent 3,840,666 ANTI-ARRHYTHMIC QUATERNARY SALT COM- POSITIONS AND METHODS OF USE Benedict R. Lucchesi, Ann Arbor, Mich., assignor to The Regents of The University of Michigan, Ann Arbor, Mich. N0 Drawing. Filed July 5, 1972, Ser. No. 269,128 Int. Cl. A611: 27/00 US. Cl. 424-329 Claims ABSTRACT OF THE DISCLOSURE 1 (N-isopropyl-N,N-dirnethylamino) 3 (l-napthoxy)propan-2-ol quaternary salts exhibit potent and longacting anti-arrhythmic activity while lacking the undesirable side-effects, e.g. B-adrenergic receptor blocking activity and local anesthetic activity, characteristic of related prior art compounds.

The invention described herein was made in the course of work under a grant or award from the Department of Health, Education, and Welfare.

The present invention is concerned with novel chemical compounds of the following formula CH3 0 CH1 C HCH1N O H CH:

CH CH CH3 wherein X- is the anion of a pharmaceutically acceptable non-toxic acid, also novel compositions containing those compounds and methods for their utilization as antiarrhythmic agents.

Anions of suitable pharmaceutically acceptable nontoxic acids are typified by the halides, e.g. chloride, bromide, iodide, fluoride, the ortho, meta and pyrophosphates, the sulfate and the alkylsulfates such as methlsulfate and ethylsulfate.

Particularly preferred anions for the purposes of this invention are the iodide and the chloride.

The compounds of the present invention are conveniently manufactured by a variety of methods. For example, a tertiary amine of the following structural formula R OCHQCHCHiN wherein R and R can be methyl radicals or R can be a methyl radical and R an isopropyl radical are contacted with the appropriate alkyl halide, alkyl sulfate or alkyl phosphate. As a specific example of this process, 1 (N isopropyl-N-methylamino) 3 (l-naphthoxy) propan-2-o1 is contacted with methyliodide in acetone, to afford 1 (N-isopropyl-N-methylamino)-3-(l napthoxy)propan-2-ol methiodide. On the other hand, l-(N,N- dimethylamino) 3 (l-napthoxy)propan-2-ol may be treated with isopropyl iodide to afford the identical product.

An alternate method for the manufacture of the instant compounds involves reaction of a secondary amine of the following structural formula 3,840,666 Patented Oct. 8, 1974 H O-CHi CHCHzN wherein R is a methyl or isopropyl radical with the appropriate alkyl halide, alkyl sulfate or alkyl phosphate. Typically, 1 (N-isopropylamino) 3 (l-naphthoxy) propan-Z-ol is contacted with two molecular equivalents of methyl chloride to yield 1 (N-isopropyl N methylamino)-3- (1-naphthoxy)propan-2-ol methochloride.

The compounds of the present invention are useful in consequence of their ability to reverse cardiac arrhythmias. They possess, moreover, the advantage of long-acting activity. These agents are furthermore, advantageously useful as compared to known anti-arrhythmic agents in that they lack the undesirable B-adrenergic receptor blocking activity of related priod art compounds. A further advantage of the compounds of this invention is their lack of local anesthetic activity.

This combination of superior effects is most unexpected and surprising in view of the fact that closely related substances do possess those side-effects. Thus 1 (N-isopropylamino) 3 (l-naphthoxy)propan 2 01 described by Lucchesi et al., Canadian Journal of Physiol. Pharmacology, 44, 543 (1966) and Lucchesi et aL, N.Y. Acad. of Sci., 139, 940 (1967), possesses the ability to reverse a wide variety of experimentally-induced arrhythmias, but suffers from the disadvantage of inducing also fl-adrenergic receptor blockade. Similarly, I (N,N diethylamino) 3 (l-naphthoxy) propan 2 ol methiodide, as described by Lucchesi et al., J. Pharm. and Exper. Therap. 162, 49 (1968) reverses experimentally-induced cardiac arrhythmias, but exhibits local anesthetic activity.

The compounds of this invention possess an additional advantage as compared to known anti-arrythmic agents in that the former substances possess the ability to decrease the vulnerability of the heart to ventricular fibrillation. This decrease in vulnerability is demonstrated by the following assay.

Experiments are performed on mongrel dogs anesthetized with pentobarbital sodium administered intravenously at a dose of 30 mg./kg. The chest is opened by a left thoracotomy incision and the heart is suspended in a pericardial cradle. The sinus node is crushed and the heart rate kept constant by electric pacing by means of an electrode sutured to the right ventricle. Vulnerability to fibrillation is assesed in the control state and repeated 30 and 60 minutes after the intravenous administration of the test compound.

The body surface electrogram is recorded from electrodes placed on the neck and left leg. To measure vulnerability to fibrillation, stimuli are delivered through silversilver chloride electrodes sutured to the right venricle. The stimulator used to deliver trains of 60 Hertz, 5 milliampere stimuli of 2 millisecond duration is coupled to the pacing stimulator so that the trains of 60 Hertz stimuli have their onset immediately after the ORS complex and are delivered every fourth to sixth basic driving stimulus. At least 3 trains of 60 Hertz of each duration are delivered before the duration of the train is increased. The trains are prolonged by 10 second increments until fibrillation occurs. The hearts are defibrillated within 5 to 10 seconds with direct current electric shocks. After control fibrillation threshholds have been determined, the animals are given the test compound and threshold determinations repeated at 30 and 60 minutes after administration. A comparable study is done in a group of control dogs which receive only 0.9% saline. Over the time course of the control experiment the threshhold to electric fibrillation does not change significantly.

Preferred compounds of the present invention are the quaternary methiodide and methochloride salts of l-(N- isopropyl-N-methylamino)-3-(1 naphthoxy)propan-2-ol. The methiodide salt, for example, possesses a wider spectrum of anti-arrhythmic activity as compared to the afore mentioned prior art compounds, while, at the same time, lacking significant fi-adrenergic receptor blocking and local anesthetic side-effects.

An especially preferred compound of the present invention is l-(N-isopropyl N methylamino)-3-(1-naphthoxy)propan-2-ol methochloride. It is advantageous in consequence of its lack of undesirable side effects which are characteristic of related compositions. It is known, for example, that iodisrn, i.e. chronic iodide poisoning, can occur in response to the administration of iodides. Chlorides, on the other hand, do not suffer from that disadvantage.

The anti-arrhythmic activity of the instant compounds and their lack of significant fi-adrenergic receptor blocking and local anesthetic side-etfects are determined by the following assays:

ACETYLSTROPHANTHIDINJNDUCED ARRI-IYTI-I- MIAS IN THE RABBIT ISOLATED HEART The rabbit isolated heart is perfused according to the Langendorff method. Male rabbits, 1.8 to 2.2 kg., are killed by cervical dislocation and their hearts are removed quickly. The perfusion solution is of the following composition, expressed as millimoles per liter: NaCl, 171.1; KCl, 2.8; CaCl -2H O, 2.0; MgCl '6H O, 2.1; dextrose, 10.0; and TI-IAM buffer, 4.1. The final solution is adjusted to a pH of 7.4 by the addition of 1 N HCl. The heart is enclosed in a double-walled glass chamber; the heart and perfusion medium are maintained at a temperature of 30 C. The perfusion solution is recycled ant. oxygenated by passing 100% oxygen into the reservoir containing the perfusion solution. Electrocardiographic recordings are made on a polygraph. The method has been described previously in greater detail by Lucchesi and Hardman, J. Pharmacol Exp. Therap., 132, 372 (1961).

OUABAIN-INDUCED ARRHYTHMIAS IN THE ANESTHETIZED DOG Male mongrel dogs, 8.3 to 12.9 kg. in weight, are anesthetized with a mixture of allobarbitol (6O mg./kg.) urethane (240 mg./kg.) and monethylurea (240 mg./l g.). (Dial-Urethane Solution, Ciba.) Blood pressures are measured from the femoral artery with a pressure transducer. All drugs are administered into the cannulated left external jugular vein. The right vagus is sectioned and its distal end is stimulated with 1.0 msec. square-Wave stimuli at a frequency of 40 cps at 6.0 to 8.0 V.

Ventricular tachycardia is induced by the administration of ouabain, 40 mg./kg. i.v., followed in 30 min. by mg./kg. and every 15 min. thereafter by an additional 10 mg./kg. until ventricular tachycardia develops (Lucchesi and Hardman, 1961).

The criteria used to determine antiarrhythmic activity are 1) reversion to normal'sinus rhythm for a period of not less than min.; and 2) the failure of right vagal stimulation to expose automatic ectopic ventricular activity during the period of vagal-induced sino-atrial nodal arrest.

Lead II electrocardiograms are monitored continuously on an oscilloscope and all recordings are made on a polygraph.

VENTRICULAR ARRHYTHMIAS AFTER CORONARY ARTERY LIGATION (a) One-step ligation Dogs are anesthetized with pentobarbital sodium, 30

mg./kg. i.v. The heart is exposed through the 5th left intercostal space. A suture is passed under the left anterior descending coronary artery, near its origin. The free ends of the suture are passed through a short section of polyethylene tubing. The artery can then be occluded by pressing the tubing onto the vessel, while at the same time pulling up on the free ends of the suture. The occlusion can be terminated by releasing the suture and pulling the tubing away from the vessel. In these experiments, acute occlusion of the anterior descending coronary artery is maintained for a period of 10 min., and if the animal survives, the occlusion is released.

Three different experiments are used on dogs studied in this fashion. In the first set of experiments, the animals are divided into control and test groups. The test group receives test compound prior to the occlusions. One to three 10 min. occlusions (with a 10 min. interval between occlusions) are performed depending on when and if ventricular fibrillation develops. The control group receives a comparable volume of 0.9% sodium chloride solution, and occlusions are performed in the same manner as in the test group. A similar study, using this technique has been describedpreviously by Lown and Wolf, CirculatiOn, 44, (1971).

In the second set of experiments, the test compound is administered at a constant infusion rate of 2.5 mg./min. When a total dose of 5 mg./kg. is attained, the left coronary artery is occluded, while still maintaining drug infusion at the constant rate. The occlusion is released after 10 minutes, and drug infusion is discontinued when the animal demonstrates normal sinus rhythm, usually 2 to 3 minutes after resumption of blood flow. After a stabilization period of 2 hours, a volume of 0.9% saline, equivalent to that of drug previously received, is administered at a constant rate, i.v. The anterior descending artery is occluded again for 10 minutes, and then released. If fibrillation ensues, it is converted electrically to a normal rhythm. Finally, 30 minutes after initiation of normal sinus rhythm, the test compound is administered again as previously described, and the anterior descending artery is occluded for 10 minutes and released. The control group of this series is treated identically, with saline being infused at all times in place of drug.

The third set of experiments deals with the anti-fibrillatory effects of test compound after release of a 20 minute occlusion of the anterior descending coronary artery. Animals are prepared and drug is infused as previously outlined. This group of animals is compared to a control group, which receives a saline infusion in place of test compound.

Finally, both 10 and 20 minute occlusions are done in the presence of propanolol, which is administered at an infusion rate and dose identical to that of test compound.

In all experiments, each dog is respired with room air by means of a respirator. vFemoral arterial pressure is measured with a pressure transducer. All drugs are administered via the left external jugular vein. Lead II EKG and all other recordings are made on a polygraph.

(b) T wo-step ligation Dogs are anesthetized with pentobarbital sodium, 30 mg./kg. i.v. A cuffed endotracheal tube is inserted and the animals are ventilated artificially with room air by a respirator. The heart is exposed by entering the chest through a left thoracotomy incision in the fourth interspace. A 2 cm. incision is made in the pericardium to expose the anterior descending coronary artery and a twostage ligation is performed according to the method described by Harris, Circulation, 1, 1318 (1950). The animals are studied 48 hours post-infarction, in the unanesthetized state, while supported in a sling and maintained in a quiet environment, during the phase of spontaneous ventricular arrhythmias.

All drugs are administered into the brachiocephalic vein, and the Lead II electrocardiogram is monitored on an oscilloscope and recorded on a polygraph. The electrocardiographic recordings are analyzed according to the method of Moran et al., J. Pharmacol. Exp. Therap., 136, 327 (1962), in which only beats of S-Z nodal origin are considered as normal and all other QRS complexes are classified as ectopic.

TESTS FOR BETA-ADRENERGIC RECEPTOR BLOCKADE (a) Isolated atrial strips Experiments are performed on atrial strips prepared from right atria removed from rabbits after cervical dislocation. The atrial strips are suspended in a 50 ml. organ bath filled with a modified Chenoweth-Koelle solution to which ethylene diamine tetraacetic acid, 1 mg. percent (disodium salt) and ascorbic acid, 2 mg. percent, has been added. The solution is of the following composition, expressed as millimoles per liter: NaCl, 120.0; KCl, 5.6; CaCl -2H O, 2.2; MgCl -6H O, 2.2; dextrose, 10.0; and NaHC 25.0. The final solution is adjusted to a pH of 7.4 by the addition of NaHCO The solution is bubbled with 95% O and CO and maintained at a temperature of 36il C. One end of the atrium is fixed to a stainless steel rod; the other end is tied to a force displacement transducer with a short segment of 40 surgical silk. The atrial strips are allowed to beat spontaneously in the bath, and measurements of peak rate are made after each dose of isoproterenol.

The muscles are allowed to stabilize for 45 min. prior to the addition of drugs to the organ bath. Cumulative concentration-effect curves for isoproterenol are determined on control strips, on atrial strips exposed for 1 hour to test compound, M, and on atrial strips exposed for 1 hour to test compound 1O M. Changes in rate are calculated as a percentage of maximal atrial rate. Probit analysis, as described by Goldstein, Biostatistics: An Introductory Text, 153-174, The MacMillan Company, New York (1964), is used to compute the effective-dose-50% (ED for each concentration-efiect curve, and these values in turn are used to calculate the pA value of test compound, according to the method described by Schild, Brit. J. Pharmacol. 2, 189 (1957).

(b) Anesthetized Dog Preparation Dogs are anesthetized with Dial-Urethane. The right ventricle was exposed through the 5th right intercostal space; the pericardium is opened and a strain gauge arch is sewn to the right ventricle. The muscle segment between the feet of the stain gauge arch is stretched to a length which gave a contraction of maximal amplitude. The animals are respired with room air by means of a respirator. Femoral arterial pressure is measured with a pressure transducer. Drugs are administered into the left external jugular vein and recordings are made on a polygraph.

Changes in isometric tension to geometrically increasing doses of isoproterenol administered i.v. are determined before and after test compound. Each dog thus serves as its own control. Statistical analysis of the data are performed by the method of paired comparisons as described by Hill, Principles of Medical Statistics, 143- 151, 172, Oxford University Press, New York (1961).

TESTS FOR INTRINSIC PROPERTIES (a) Isolated atrial strips Isolated right atria from 9 rabbits are used (Weight 2.2- 2.8 kg.). The atria are permitted to equilibrate for minutes and the spontaneous atrial rate is recorded every 10 min. for the next 60 min. When the atrial rate has stabilized, the preparation is exposed to test compound in concentrations ranging from 10- M to l0 M inclusive. Subsequent addition of test compound is made at 30 minute intervals. The spontaneous atrial rate is determined every 10 minutes.

(b) Anesthetized Dog Preparation Dogs, anesthetized with Dial-Urethane are used to test the effects of the drug on resting heart rate and force of contraction. The heart is exposed via a right thoracotomy and a strain gauge arch is sutured to the right ventricle. Heart rate is recorded with a tachograph. All recordings were made on a polygraph.

(c) Local Anesthetic Activity Female frogs (Rana pipiens) are decapitated and the sciatic-tibialperoneal nerves (sciatic trunk) are removed bilaterally and placed in frog Ringers solution. The Ringers solution is of the following composition, expressed as millimoles per liter: NaCl, 111; KCl, 2.7; CaCl -2H O, 1.4; and NaHCOg, 2.4. The solution had a pH of 7 .4 and is maintained at a temperature of 25 C. In one series of experiments the epineurium of the nerve is removed by the method of Feng and Liu, J. Cell. Comp. Physiol. 34, l (1949).

The experimental design has been described in greater detail previously by Lucchesi and Iwami, J. Pharmacol. Exp. Therap., 162, 49 (1968). Briefly, a sciatic trunk is passed through a plastic T-tube, and both are mounted on platinum electrodes in a nerve chamber with a humidified atmosphere. Ringers solution can then be pumped at a constant rate into the vertical limb of the T-tube. The pump also serves to remove fluid from the chamber at this same rate.

Monophasic spikes are recorded by crushing that part of the nerve in contact with the distal recording electrode. The nerves are stimulated at their peripheral ends so as to producea maximal spike potential for the A a group of fibers. Since the height of the spike is an index of the number of fibers conducting impulses, and since the response is maximal, any reduction in spike height can be attributed to a block of some fibers in the treated segment. The action potential is amplified through a preamplifier, displayed on a oscilloscope and photographed. Spike potentials are photographed every 15 min. for 1 hour, starting with the time drugs are applied to the nerve trunks. The percent change from control spike amplitude is calculated from the photographed tracings.

The compound solutions employed in the above assays are prepared in the following manner:

Crystalline acetylstrophanthidin is dissolved in the perfusion medium used in the Langendorfi preparation; the final concentration of the stock solution is ,ug./ml. Solutions of ouabain are prepared by dissolving the crystalline material in 0.9% sodium chloride solution to give a final concentration of 80 g/ml. Solutions of isoproterenol are made daily from l-isoproterenol bitartrate (Sigma Chemical Co., St. Louis, Mo.) dissolved in a solution of ascorbic acid, 1 mg. percent. Procaine HCl is dissolved in Ringers solution in a concentration of 10* M. Solutions of test compound are made daily by dissolving the crystalline material in 0.9% NaCl solution to give a final concentration of 5 mg./ml. for the intact dog experiments. For the isolated tissue experiments, test compound is dissolved in the respective perfusion media appropriate for the particular experiment.

The novel compositions of this invention consist of one of the aforementioned active ingredients combined with a pharmaceutically acceptable carrier. These compositions can be administered either orally or parenterally. For oral administration tablets, lozenges, capsules, dragees, pills or powders are suitable, while aqueous solutions, non-aqueous solutions or suspensions are appropriate for parenteral administration. Acceptable pharmaceutical carriers are exemplified by gelatin capsules, sugars such as lactose or sucrose, starches such as corn starch or potato starch, cellulose derivatives such as sodium carboxymethyl cellulose, ethyl cellulose, methyl celiulose or cellulose acetate phthalate, gelatin, talc, calcium phosphate such as dicalcium phosphate or tricalcium phosphate, sodium sulfate, calcium sulfate, polyvinylpyrrolidone, acacia, polyvinyl alcohol, stearic acid, alkaline earth metal stearates such as magnesium stearate, vegetable oils such as peanut oil, cottonseed oil, sesame oil, olive oil, corn oil or theobroma, water, agar, alginic acid, benzyl alcohol, isotonic saline and phosphate buffer solutions as well as other non-toxic compatible substances.

The instant method for reversing arrhythmias in mammals comprises the administration of a novel composition of this invention containing a therapeutically effective amount of the active ingredient. The term therapeutically effective amount is defined as the amount of active ingredient that will produce an anti-arrhythmic effect. For a particular subject the actual amount of active ingredient to be used will vary with the nature of the subject, the severity of the arrhythmia, the route of administration and the particular active ingredient used. A recommended dosage range for parenteral, e.g. intravenous, administration if 1-10 mg., repeated as needed. For oral administration, a dosage range of 40-500 mg./day is preferred.

The compositions of the present invention can be used also in combination with other known pharmaceutical agents. For example, they can be used together with known anti-anginal agents such as the long-acting nitrites. They can, furthermore, be utilized in combination with other known anti-arrhythmic agents such as quinidine. In addition, they can be used in combination with known hypotensive agents.

The invention will appear more fully from the examples which follow. They are not to be construed as limiting the invention either in spirit or in scope as variations both in materials and in methods will be apparent to those skilled in the art. In the following examples, temperatures are given in degrees Centigrade C.) and quantity of materials in parts by weight unless parts by volume is specified.

EXAMPLE 1 A mixture of 11 parts of l-(N-isopropyl-N-methylamino)-3-( l-naphthoxy)propan-2-ol, 13.6 parts of methyl iodide and 176 parts of benzene is stirred at room temperature for 3 days. The benzene layer is decanted from the oil which forms and the oil is slurried in ethanol and crystallized. The crystals are recovered by filtration and recrystallized from methyl ethyl ketone, thus affording 1-(N-isopropyl-N-methylamino) 3 (1-naphthoxy)propan-Z-ol methiodide. That compound melts at aout 160- 16l and is represented structurally by the following formula I (511 L CH3 w e CH3 CH8 EXAMPLE 2 A mixture of 6.0 parts of l-(N-isopropyl-N-methylamino)3-(l-naphthoxy)propan-2-ol, 4.5 parts of methyl chloride and 40 parts of methyl ethyl ketone is allowed to stand in a steam cabinet for about 18 hours. After that time an oil forms and the mixture is cooled in an ice bath, whereupon crystallization occurs. The solid crystals are recovered by filtration and dried, then dissolved in a mixture of methanol and methyl ethyl ketone. The methanol is removed by boiling. The solution is cooled and seeded to afford pure 1-(N-isopropyl-N-- methylamino)-3-(1 naphthoxy)propan-2-ol methochloride. That compounds melts at about 168-171 and is represented by the following structural formula What is claimed is: 1. A pharmaceutical composition which comprises a therapeutically effective amount of a compound of the formula CH3 o-cniortcnrf l CH CH wherein X- is the anion of a pharmaceutically acceptable non-toxic acid, together with a suitable pharmaceutical carrier.

2. A pharmaceutical composition as in Claim 1, wherein X is a chloride, bromide, iodide, fluoride sulfate, alkyl- CH: CH:

oomoncm-fi wherein X- is the anion of a pharmaceutically acceptable non-toxic acid, together with a suitable pharmaceutical carrier.

6. A pharmaceutical composition as in Claim 1, for parenteral administration, which comprises 1-10 mg. of a compound of the formula wherein X- is the anion of a pharmaceutically acceptable non-toxic acid, together with a suitable pharmaceutical carrier.

7. A method of treating cardiac arrhythmias in mammals which comprises administering to said mammals a therapeutically effective amount of a compound of the formula O-CHzCHCHPN X" (5 H J; CHa

CH3 CH wherein X- is the anion of a pharmaceutically acceptable non-toxic acid.

8. As in Claim 7, a method of treating cardiac arrhythmias in mammals which comprises administering to said mammals a therapeutically effective amount of a compound of the formula 10 10. As in Claim 7, a method of treating cardiac arrhythmias in mammals which comprises administering to said mammals a therapeutically efiective amount of 1- (N-isopropyl N methylamino)-3-(1-naphthoxy)propan-Z-ol methochloride.

References Cited Lucchesi et al., Chem. Abst., vol. 69 (1968), page 25927v.

Crowther et al., Chem. Abst., vol. 70 (1969), page 3607 Crowther et al., Chem. Abst., vol. 63 (1965), page 6933c.

SAM ROSEN, Primary Examiner US. Cl. X.R. 260567.6 M 

1. A PHARMACEUTICAL COMPOSITION WHICH COMPRISES A THERAPEUTICALLY EFFECTIVE AMOUNT OF A COMPOUND OF THE FORMULA 